Daniel Herzog, Mason Co., IL

My Gt. Grandfather Daniel Herzog came to America in about 1850 when he was about 26 years old.He married Dolly Lowe from Kentucky and settled in Salt Creek Township in Mason Co., IL, where he lived until 1899.I have found a possible ship record for the President Smidt from Bremen to New Orleans that landed May 24, 1850.This Daniel was listed as a tailor, 26, from Nahlhof.Does anyone know of sources in Germany or Illinois where I might find more.I have his obituary, picture, wedding liscense, naturalization paper, and census records, but nothing gives his birthplace other than Germany or his parents name. Help! Where do I go next?